Carburetor



@ct, 25, W32. A. KAZENMAIER CARBURETOR Filed Aug. 11. 1930 Patented Oct.25, 1932 UNITED "STATES PATENT] OFFICE AUGUST KAZENMAIER, OF STUTTGART,GERMANY, ASSIGNOR TO ROBERT BOSCH AKTIENGESELLSCHAFT, OF STUTTGART,GERMANY CARIBURETOR Application filed August n, 1930, Serial No.474,477, and in Germany September 11, 1929.

The present invention relates to self-feeding carburetors having airthrottle and float chamber regulation in which the air space of thefloat chamber is connected to one choke tube whilst the fuel space ofthe float chamher is connected to another choke tube in which the vacuumis higher than in the first choke tube. In order to prevent anexcessively high vacuum arising in the mixing chamber when the airthrottle is closed, the mixing chamber of this carburetor can be closedfrom the engine by a throttle to such an extent that the vacuum arisingin the mixing chamber only reaches that degree which is necsssary formaintaining the fuel level at the required height in the float chamberthat is to say to be able to supply the fuel from a low lying supplytank to the float chamber. As the two throttles are moved together andtherefore opened and closed together vacuum is increased in the mixingchamber wh III the throttles are opened because the high vacuum behindthe suction throttle can suddenly act much more strongly on the mixingchamber,

' and it is not possible for suflicient fresh air to flow through theopening to the choke tube.

In order to avoid this undesirable increase of the vacuum in the mixingchamber the two throtfies are so connected together according to thepresent invention that the air throttle at least at the beginning openscorrespondingly more quickly than the suction throttle behind the choketubes. Fuel is saved in this way and in addition the suction noise isreduced.

One form of construction according to the invention is shown by way ofexample in the accompanying drawing.

The mixing tube a has a main choke tube 6 in which is disposed anauxiliary choke tube a. V The throat of the nozzle 6 is connected to theair space of afloat chamber 6 by a passage d. A pipe f leads from thefuel space of the float chamber to the throat of the nozzle 0. Aconstriction a is provided in the pipe f for governing the passage offuel. The air throttle h has a lever 2' which is connected through a rod70 to a lever m of the throttle valve 11.. Behind the choke tubes 6, c,is a calibrated opening 0 in the mixing tube a for regulating the vacuumwhen the throttle n is closed.

The levers i and m) are secured to their axles in such a way that therod it makes an acute angle a With the lever i and an obtuse angle ,8with the lever m when both throttle valves are closed. Whenv thethrottle valve k is opened for an angle y the throttle valve 'n. opensfor only the substantially smaller angle 8. The levers i and m and thethrottle valves h and n are preferably so disposed from each other thatthe two throttle valves simultaneously move into their end position tobe opened completely. (See the dotted lines in the figure.)

I claim:

1. A self feeding carburetor comprising a mixing tube, at least twochoke tubes adapted to produce different degrees of Vacuum for any givenengine suction, a float chamber the air space of Which is connected tothe choke tube of lower vacuum and the fuel space to the choke tube ofhigher vacuum, an air throttle in advance of said choke tubes, a secondthrottle in rear of said choke tubes and means for operating said secondthrottle in depend ence on said air throttle such that the rate ofincrease of effective cross sectional area past the air throttle isgreater on commencement of opening of the same than that past the secondthrottle.

2. A self feeding carburetor comprising a mixing tube, at least twochoke tubes adapted to produce different degrees of vacuum for any givenengine suction, a float chamber the air space of which is connected tothe choke tube of lower vacuum and the fuel space to the choke tube ofhigher vacuum, an air throttle in advance of said choke tubes, a secondthrottle in rear of said choke tubes, operating levers on said air andsecond throttles and a connecting link between said levers,

the disposition of said levers and connecting link being such that .whenthe throttles are closed the lever of the air throttle forms a smallerangle with said link than the lever of the second throttle.

3. A self feeding carburetor comprising a mixing tube, at least twochoke tubes adapted to produce different degrees of vacuum for any givenengine suction, a float chamber the air space of which is connected tothe choke tube of lower vacuum and the fuel space to the choke tube ofhigher vacuum, an air 5 throttle in advance of said choke tubes, asecond throttle in rear of said choke tubes, operating levers on saidair and second throttles and a connecting link between said levers, thedisposition of said levers and connecting link being such that when saidthrottles are closed the effective length of the lever of the airthrottle is less than the efiective length of the lever of the secondthrottle so that the rate of increase of effective cross sectional areapast the air throttle is greater on commencement of opening of the samethan that past the second throttle 4. A self feeding carburetorcomprising a mixing tube, at least two choke tubes adapted to producedifferent degrees of vacuum for any given engine suction, a floatchamber the air space of which is connected to the choke tube of lowervacuum and the fuel space to a the choke tube of higher vacuum, an airthrottle in advance of said choke tubes, a second throttle in rear ofsaid choke tubes and common operating means for opening and closing saidthrottles simultaneously, said meansoperating on commencement of open- 3ing movement to rotate the air throttle faster.

than the second throttle.

5. A self feeding carburetor comprising a mixing tube, at least twochoke tubes adapted to produce diflerent degrees of vacuum for any givenengine suction, a float chamber the air space of which is connected tothe choke tube of lower vacuum and the fuel space of. which is connectedto the choke tube of higher vacuum, an air throttle in advance of saidchoke tubes, a second throttle on rear of said choke tubes, means foroperating said second throttle in dependence on said air throttle suchthat the rate of increase of efiective cross sectional area past the airthrottle is, greater on commencement of opening of the same than thatpast the second throttle, said operating means being further adapted tocause the throttles to reach their fully open or fully closed positionssimultaneously.

In testimony whereof I have hereunto atfixed my signature.

AUGUST KAZENMAIER,

